I am not a scientist. I have only a little expertise on how people who are scientists practice it. And my interest in science is mild to moderate. But that moderate interest is good enough to make me a fan of so many animal sciences (branches of zoology, primarily), because of my love for animals and fascination with their behavior. And as a lover of animals, I feel that a favor should be given to those that are among the most intelligent and emotional. People should initiate the concept of animal personhood.
I have a stance that's similar to the one held by scholar Steven Wise. Some animals meet the criteria of legal personhood, and should therefore be awarded certain rights and protections. The animals must do the following to be like "animal people." The animal must desire things, and can act in an intentional manner to acquire those things. They can't just instinctively know the base things they need for survival. They also must have a sense of self, and self-awareness, too. They must know that they exist. And finally, they must display some semblance of feelings, or at least simple emotions, as well as animal thoughts. An animal that can't feel is emotionless, and thus, is often base in nature.
I agree with Wise's opinion that the following animals meet that criteria: chimpanzees, bonobos, elephants, parrots, dolphins, orangutans, and gorillas. I could add several more to that list myself, despite my lack of experience with science. If apes and dolphins are capable of personhood, logically, monkeys, porpoises and whales would probably fit the category, as well, and crows and ravens are some of the most intelligent birds alive, so they and their close relatives, the magpie and the jay, more or less fit the criteria, too. Dogs, both domestic and wild, fit the criteria in my professional and personal opinion, and possibly also cats, especially lions and domestic cats. Let's look at a few of the ways each of them is like a person, based on my knowledge and education.
Chimpanzees and bonobos...They have the most human-like appearance of all animals, to begin with, but that's pretty obvious. They have social groups full of many individuals, and they have their leaders of the groups, too. With chimps, it's the males, and with bonobos, it's the females. They use hands instead of front paws or claws, and have opposable thumbs to hold things. Their faces are much like human faces, and they show emotional expressions. They can even communicate with sign language, and can "talk" with the help of a lexigram. Chimps fiercely protect their territory, get into fights as well as friendships, and make tools for various purposes, like getting at termites. Bonobos also use tools, but they are much more peaceful than common chimps, and use sex as a means to achieve that peace. There are too many things for me to list all of them here, but you get the general idea.
Elephants...While elephants don't look like people, they make up for that in a few ways. Elephant mothers care greatly for their young, and evidently, little elephants seem to feel a bond with their mothers. If one or the other suffers or dies, then the other will feel sorrow and emotional suffering at the loss. In fact, it appears that all elephants mourn their dead, even if they are total strangers. If an elephant in the wild comes across an elephant carcass, they will stay by it for a long time, and touch and brush against it with their trunks. Elephants obviously have the intelligence and the feelings to recognize their own mortality, and acknowledge it as well.
Parrots...One might think it odd that these birds could be considered people. I know, I did myself once. But parrots are smart enough to recognize human speech, and unlike virtually all other animals, including chimps and bonobos, they can speak, or at least mimic our speech. In addition to repeating what we say, sometimes they can learn how to say their own words or sentences, like if they're commenting on something, or they're making a request. Remember the old pirate parrot saying, "Polly wants a cracker!"
Dolphins, porpoises, and whales...The ocean's cetaceans are extraordinary. They can communicate, too, by sending signals, like dolphins and porpoises, or by singing their haunting songs, like the bigger whales, and most memorably, the Humpback Whale. We have yet to tell exactly what it is they are saying, or singing, but scientists are still working on it. They are also experts at doing stunts, like some humans, as they demonstrate at dolphin shows and at sea, and maybe most importantly, they can make lasting friendships and even bonds with other creatures, especially us humans. They seem to understand much of our body language, and they do their best to imitate it, too.
Orangutans...These animals are like people in much the same way that chimpanzees and bonobos are. They make tools, they have arms, hands, and opposable thumbs, and they bond with their babies. But the orangutan stands out for a few other reasons, too. Per its name, "old person of the forest," it is like a wise old man living in the forest by himself, taking life easy, and trying to live like a hermit. Orangutans are like people that live in slow motion and have all the time in the world.
Gorillas...The biggest of the great apes is, of course, like the others in many ways, but they don't make tools. They make a show of aggression, but are seldom actually violent, they live in family groups like most people do at some point in their lives, they have a dominant male, they live lives of organized peace, and their families are fiercely protected by the dominant male, who fights to protect his family group.
Capuchin monkeys...The most intelligent of the New World monkeys, the capuchin is known for using tools, just like the chimpanzee and the orangutan. They use stones and other hard things to crack open fruits and nuts, and they can also crush millipedes and rub their crushed bodies on their backs to form an insect repellent. They have some sense of self, and they live in social groups, just like most other primates do.
Other monkeys...To some extent, all monkeys, especially the Old World baboons and macaques, are self-aware and have the intelligence needed to seem like animal people. Besides having feelings and complex thoughts, some of them also beg for things from human settlements, or even steal them from under the humans' noses. While not on the same level of intelligence as their cousins, the apes, monkeys are still smart animals, and except for their tails, they too bear a superficial resemblance to human beings.
Ravens and crows...I have learned some interesting things about these birds, especially ravens, and how they are some of the smartest birds in the world. Ravens and crows can count things like a human, such as their eggs and their babies, only without speech. But there are some people who claim that ravens and crows actually can speak. They definitely have a high learning ability and can use logic for solving problems. They even express emotions in their calls, like tenderness, happiness, surprise, rage, and possibly sorrow. And of course, they're attracted to shiny things and love to take them and keep them, meaning that they desire things and are capable of getting them.
Dogs, wolves, coyotes, jackals, and dingoes...It doesn't take a genius to figure out why dogs, domestic and wild, are like people. All of these beasts show emotions like courage, fear, happiness, sadness, kindness, anger, and others. They are doting mothers and fathers, taking excellent care of their puppies and pups, and keeping their litters neat and orderly. They desire delicious food so much, they'll even beg for it from a human, particularly a domestic dog, and they can form lasting friendships and love relationships with humans that feed them and/or take care of them. And of course, they are smart animals, being able to count the puppies in their litters, knowing how to retrieve lost things and sniff out other things, like drugs, and understand exactly how their masters and other people around them are feeling. They couldn't be such soul mates without personhood.
Cats, big and domesticated...While not as caring about others' feelings as dogs, cats do take good care of their young, and mother cats seem to love their kittens almost as much as mother dogs love their puppies. Cats keep an eye on their kittens with a passion, always making sure that their young remain safe and happy, and if dogs or other animals threaten that peace, they execute the old policy: No dogs allowed! Cats also hang around their owners for a choice feast or treat, and they seem to show a little bit of enjoyment for eating their favorite foods. These things are especially true with domestic cats; wild cats usually don't have owners, and are more dangerous, so we don't know as much about their personhood.
To sum up, if these animals are indeed "person animals," then they should have legal personhood bestowed upon them to protect them from "serious infringements upon their bodily integrity and bodily liberty." These animals need personhood in law, because without it, one is "invisible to civil law" and "might as well be dead," as Steven Wise puts it.
Of course, as a Christian, I'm not saying that these animals should be equal in every way to man. I know God created man alone in His image, and woman as well, to be his personal children and caretakers of the Earth, and God likely loves his humans the most of all things he has created. But it would show some care for these wise animals, as well as a feeling of identity and individuality, if they were treated as citizens, too, or at least people, just not human people.